An electron having mass 'm' and kinetic energy E enter in uniform magnetic field B perpendicularly, then its frequency will be :-

Question

( A ) $\frac{eB}{2 \pi m}$
( B ) $\frac{2m}{eBE}$
( C ) $\frac{2 \pi m}{eB}$
( D ) $\frac{eE}{qVB}$